1. Field of the Invention
The present invention relates to modules incorporating a capacitor, methods for manufacturing the same, and capacitors used therefor.
2. Description of the Related Art
In recent years, with the progress in the miniaturization of various devices and the increase in density of capacitors constituting the devices, there is an increasing demand for the miniaturization of the capacitor itself. Moreover, with the development of higher speed devices, high-speed response and low-loss properties are demanded for capacitors equipped with a capacitor unit. In order to meet these demands, three-dimensional modules incorporating a capacitor in which a capacitor or a semiconductor component (active component) provided with a capacitor is incorporated in a substrate have been developed vigorously (see e.g., JP H11-220262A).
At this time, in order to attain both a higher density and a reduced thickness for capacitors constituting a module incorporating a capacitor, it is necessary to use a high-performance capacitor whose size and thickness are small. However, as the size and the thickness of the capacitors become increasingly small, the handling and the mounting of the capacitors have become particularly difficult.
When the capacitor unit is a capacitor, a film-type solid electrolytic capacitor is suitable as a capacitor to be incorporated in a substrate for producing a small or thin module incorporating a capacitor. However, the film-type solid electrolytic capacitor is particularly difficult to handle as a single component, since it is extremely thin although having a large capacitance.
Here, a conventional film-type solid electrolytic capacitor is described with reference to FIG. 12. FIG. 12 is a cross-sectional view showing the configuration of a typical conventional film-type solid electrolytic capacitor. The conventional film-type solid electrolytic capacitor shown in FIG. 12 is provided with: an anode valve metal 121, such as aluminum; a dielectric oxide film 122 formed on the surface of the anode valve metal 121; a solid electrolyte layer 123 that contains a conductive polymer, such as polypyrrole, as a solid electrolyte, and is formed on a portion of the surface of the dielectric oxide film 122; and a cathode current collector layer 124, such as a carbon layer or an Ag (silver) paste layer, formed on the surface of the solid electrolyte layer 123; and an insulating resin portion 125 formed on a portion of the surface of the dielectric oxide film 122 (see e.g., pars. [0003] and [0004] and FIG. 11 of JP2002-198264A). It should be noted that in the conventional film-type solid electrolytic capacitor shown in FIG. 12, the insulation between the anode valve metal 121 and the cathode current collector 124 is ensured by providing the insulating resin portion 125.
Since such a film-type solid electrolytic capacitor generally has a thickness of 0.2 mm or less, it tends to be deformed by an external force and physically damaged. Therefore, instead of handling the film-type solid electrolytic capacitor as a single component, a plurality of the film-type capacitors are enclosed in a package to form a chip, thus preventing deformation or damage, while allowing them to be handled readily by suction utilizing an air pressure difference (see e.g., FIGS. 1 and 3 of JP H6-168855A).
Usually, when a capacitor is mounted using a mounting device such as a chip mounter, the capacitor is first held (by vacuum suction) by a transport member with an air pressure difference, then moved to a desired position on a substrate, with the capacitor held by the transport member, followed by separating the capacitor from the transport member by suspending the vacuum suction. Therefore, it has been difficult to mount on a substrate a single conventional capacitor unit, which is small and has weak mechanical strength, as a single component.
In the case of the film-type solid electrolytic capacitor, it has been particularly difficult to handle the capacitor as a single component, since it is small and very thin, with its thickness being 0.2 mm or less. Furthermore, when such a film-type solid electrolytic capacitor is mounted onto a substrate as a single component, the functions of the capacitor may be damaged fatally by, for example, peeling of the surface layer. Moreover, the surface layer is not flat, so that a sufficient suction force may not be obtained by vacuum suction and a suction failure or falling thus may occur during transporting the capacitor. Therefore, it has been extremely difficult to perform a conventional automatic mounting.
On the other hand, a conventional capacitor formed as a chip by enclosing a plurality of capacitors in a package can be handled more easily, than a capacitor as a single component. However, in this case, the capacitor becomes large physically, and a plurality of capacitor units are concentrated on the same portion on the substrate, hindering the flexibility of the circuit design. This results in the necessity to provide a more complex or longer wiring. Furthermore, when the conventional capacitor formed as a chip is embedded in a multi-layered circuit board, it is necessary to provide an insulating layer of a thickness corresponding to the height of the capacitor. Therefore, in the case of using the conventional capacitor formed as a chip, it has been difficult to realize a further reduction in the size and the thickness of a module incorporating a capacitor.